High-flow nasal cannula oxygen therapy obscures severe respiration depression, providing an illusion of safety

Impact of a simple non-invasive nasal mask device on intraprocedural hypoxemia in overweight individuals undergoing upper gastrointestinal endoscopy with sedation provided by a non-anesthesiologist provider

BACKGROUND/AIMS

Hypoxemia is a common side effect of propofol sedation during endoscopy. Applying mild positive airway pressure (PAP) using a nasal mask may offer a simple way to reduce such events and optimize the conditions for diagnostic and therapeutic upper gastrointestinal endoscopies.

METHODS

We compared overweight patients (body mass index >25 kg/m2) with a nasal PAP mask or standard nasal cannula undergoing upper gastrointestinal endoscopies by non-anesthesiologists who provided propofol sedation. Outcome parameters included the frequency and severity of hypoxemic episodes.

RESULTS

We analyzed 102 procedures in 51 patients with nasal PAP masks and 51 controls. Episodes of hypoxemia (oxygen saturation [SpO2] <90% at any time during sedation) occurred in 25 (49.0%) controls compared to 8 (15.7%) patients with nasal PAP masks (p<0.001). Severe hypoxemia (SpO2 <80%) occurred in three individuals (5.9%) in both groups. The mean delta between baseline SpO2 and the lowest SpO2 recorded was significantly decreased among patients with nasal PAP mask compared to controls (3.7 and 8.2 percentage points difference, respectively). There were significantly fewer airway interventions performed in the nasal PAP mask group (15.7% vs. 41.2%, p=0.008).

CONCLUSION

Using a nasal PAP mask may be a simple means of increasing patient safety and ease of examination.

Hypercarbia and high-flow nasal oxygen use during anaesthesia - risking a failure to thrive?

Prevention of arterial oxygen desaturation during anaesthesia with high-flow nasal oxygen (HFNO) has gained greater acceptance for a widening range of procedures. However, during HFNO use there remains the potential for development of significant anaesthesia-associated apnoea or hypoventilation and the possibility of hypercarbia, with harmful cardiovascular or neurological sequelae. The aim of this study was to determine whether any HFNO-related hypercarbia adverse incidents had been reported on webAIRS, an online database of adverse anaesthesia-related incidents. Two relevant reports were identified of complications due to marked hypercarbia during HFNO use to maintain oxygenation. In both reports, HFNO and total intravenous anaesthesia were used during endoscopic procedures through the upper airway. In both, the extent of hypoventilation went undetected during HFNO use. An ensuing cardiac arrest was reported in one report, ascribed to acute hypercarbia-induced exacerbation of the patient's pre-existing pulmonary hypertension. In the other report, hypercarbia led to a prolonged duration of decreased level of consciousness post procedure, requiring ventilatory support. During the search, an additional 11 reports of postoperative hypercarbia-associated sedation were identified, unrelated to HFNO. In these additional reports an extended duration of severe acute hypercarbia led to sedation or loss of consciousness, consistent with the known effects of hypercarbia on consciousness. These 13 reports highlight the potential dangers of unrecognised and untreated hypercarbia, even if adequate oxygenation is maintained.

High flow nasal oxygen during procedural sedation for cardiac implantable electronic device procedures: A randomised controlled trial

BACKGROUND

High flow nasal oxygen may better support the vulnerable respiratory state of patients during procedural sedation.

OBJECTIVE

The objective of this study was to investigate the effects of high flow nasal oxygen in comparison to facemask oxygen on ventilation during cardiac implantable electronic device procedures performed with procedural sedation.

DESIGN

A randomised controlled trial.

SETTING

The study was conducted at one academic hospital in Canada.

PARTICIPANTS

Adults undergoing elective cardiac implantable electronic device procedures with sedation administered by an anaesthesia assistant, supervised by an anaesthesiologist from August 2019 to March 2020.

INTERVENTIONS

Participants were randomised 1 : 1 to facemask (≥ 8 l · min-1) or high flow nasal oxygen (50 l · min-1 and a 50 : 50 oxygen to air ratio).

MAIN OUTCOME MEASURES

The primary outcome was peak transcutaneous carbon dioxide. Outcomes were analysed using Bayesian statistics.

RESULTS

The 129 participants who were randomised and received sedation were included. The difference in peak transcutaneous carbon dioxide was 0.0 kPa (95% CI -0.17 to 0.18). Minor adverse sedation events were 6.4 times more likely to occur in the high flow nasal oxygen group. This estimate is imprecise (95% CI 1.34 to 42.99). The odds ratio for oxygen desaturation for the high flow nasal oxygen group compared with the facemask group was 1.2 (95% CI 0.37 to 3.75). The difference in satisfaction with sedation scores between groups was 0.0 (95% CI -0.33 to 0.23).

CONCLUSIONS

Ventilation, as measured by TcCO2, is highly unlikely to differ by a clinically important amount between high flow nasal oxygen at 50 l min-1 or facemask oxygen at 8 l min-1. Further research with a larger sample size would be required to determine the optimal oxygen:air ratio when using high flow nasal oxygen during cardiac implantable electronic device procedures performed with sedation.

TRIAL REGISTRATION NUMBER

NCT03858257.